Vacuum control of spark advance



Sept. 27, 1938.

J. ARTHUR 2,131,020

VACUUM CONTROL OF SPARK ADVANCE 108 ,zzo m5 220 122 zzs "353* I 2 12 (Z 5 7 234 m E A M4 I 704 me INVENTOR James LArZ/zu 7".

ATTORNEYS Sept. 27, 1938.

ENG/NE ENG/NE DEGREES ADVANCE 4ND DEGREES 7' HFOTTLE OPEN A'NG/NE- p. P. M. I60

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MIL E5 PER-HOUE 0 A U E 5 MILE-S'PEP-HOUR INVENTOR ATTORN EY 3 Sheets-Sheet 3 a 8 1 '3' Q 8 52. PERCENT THPOT 1- PEPCEN T THEO 7' TL E OPEN/N 6 James L.A7"Zhu7:

ing conditions.

Patented Sept. 27, 1938 UNITED STA ES PATENT OF VACUUM CONTROL OF SPARK ADVANCE James L. Arthur, Anderson, Ind., assignor to General Motors Corporation, Detroit, Mich, a corporation of Delaware Application February 24, 1936, Serial No. 65,358

\ 27 Claims.

ing a movable part linked to an adjustable part of a timer mechanism, responds to low pressures within the fuel induction pipe, when in communication therewith through an appropriate valved passage, for moving the adjustable timer part to effect a change in ignition timing. By the Stone construction, it is proposed to cut off the application of reduced pressure to the contraction chamber, while the engine is running at idle, so that a spring incorporated in the contraction device will effect a retard of 'timing, and thence it is also proposed to admit the low pressure to the contraction chamber in varying and increasing amounts as the throttle valve is opened beyond idling position, so that an increasing advance of timing will be effected for the corresponding engine speeds.

While there are many prior art devices directed to the same art, of which Stone above men-' tioned is but a single example, all of the prior art 30,devices fail to give complete control of ignition timing for all conditions of engine speed and car road torque. One particular point at which the prior art devices fail, is in giving .any adequate control of ignition timing, for the higher speeds 5 of the entire speed range. The prior art devices, therefore, ignore the fact that it is necessary from a standpoint of eiiiciency, or that it is at all desirable to modify the automatic advance intiming during the higher speed operat- As a result, timer control mechanisms of the prior art devices give too great a shift of automatic timing, and continue the shift by automatic mechanism over too great a range of enginespeed. In other words, the automatic shift of spark timing lasts too long and extends too far toward the high speed end of the engine speed range. I

It has been discovered by applicant, that for best efllciency and economy in engine operation, there is possible a basic control of spark timing by speed responsive mechanism, that will fit fairly closely the minimum demands for average operating conditions, and upon which basic control there is to be superposed further control that will take care of the extremes of demands for timer regulation. This basic control is what may be called an initial timer setting, to which is joined a normal control of spark advance by speed responsive mechanism. Over this basic control, it is desired to have no timer shift at or during 5 engine starting and idling speeds, and during the extreme high engine speeds, but to produce a rather abrupt and fixed amount of timer shift throughout the band of engine speeds situated between the idling speeds and the extreme high 10 speeds, which latter shift shall be superposed over the centrifugal or normal control.

It is therefore an object of this invention to provide for effecting ignition timer control throughout the entire range of engine speeds 15 and/or vehicle road torques.

'A further object of the invention is to provide a method for controlling a suction operated timer shifting mechanism, such that a retarded spark timing relation will be accomplished for engine 20 starting and idling, such that a substantial fixed amount of advance spark timing will obtain for all moderate engine speeds above idling, and such that the advance of ignition timing will be reduced to a basic control for higher engine speeds, 5 or' for those speeds greater than moderate engine speeds.

Another object of the invention is to make use of the throttle shaft, when opened to a certain position, as a cut-out for spark control connec- 30 tions.

Another object'of the invention is to accelerate the cut-off of the motive unit at a designated point in the range of engine speeds.

A still further object is to provide a passage in 3 the throttle shaft, opening into. the carburetor side of the throttle valve so as to drop the vacuum at the distributor diaphragm when the engine and car road torque reaches the point where the spark should be retarded, particularly at high 40 speed.

These several objects are accomplished by means of an interruptible passage, joining the fluid connections to the contraction unit, and controllable for negativing the suction effect within the fuelinduction pipe upon the contraction unit at a selected point or points in the range of throttle movement.

Part of the interruptible passage includes a cross-bore or duct through the fuel throttle shaft, and so located that shaft rotation will establish communication between the cross-bore and the fluid connection to the contraction unit only at a desired relation of throttle opening. At that desired relation, the contraction unit is exposed 55 I to the low pressure zone through a primary passage, and the newly effected communication throughthe interruptible passage forms a bypass around the primary passage to the high pressure zone of the induction pipe. When the throtto the point where the by-pass communication is sufficiently established, the contraction unit is then exposed to the combined efiect of the fluid pressure of the low pressure zone. at the primary port, and of the high pressure zone at the orifice of the interruptible passage. In consequence of the latter, a complete retraction of the advance mechanism is effected soon after communication is perfected between the interruptible passage and the primary passage.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention 'is clearly shown.

In the drawings:'

Fig. l is a view illustrating the layout of the timer control mechanism forming the .subiect matter of the instant invention, certain parts of the construction being shown in section, and certain other parts being broken away for the purpose" of clear illustration.

Fig. 2 is a view in elevation, with parts shown in section, illustrating parts of the fluid connection to the engine intake pipe, when the throttle valve has been opened to a point above idling speeds. The section taken is indicated by the line and arrows 2 -2 of Fig. 4.

Fig. 3 is a view similar to Fig. 2, illustrating the throttle valve ,open to a greater degree, and

at which position the interruptible passage is being opened.

- sectional view through the fuel induction pipe,

substantially at the axis of the throttle shaft, while Fig. '7 is an elevational view of the same, showing. parts in section substantially as indi, cated by the line and arrows 1-1 of Fig. 6. Figs. 8 and 9 are views similar to Fig. 7, the throttle valve having been moved to different positions. Fig. 10 is a layout somewhat similar to Fig. l, but illustrating the throttle valve in the wide open position, and the contraction unit in its resulting condition.

Fig. 11 is a group of conditions curves, illustrating the pressures obtainable in inches of mercury (Hg) depression, for various engine speeds.

Fig. 12 is a group of results curves illustrating the. timing alterations that may be efiected by the mechanism disclosed.

Referring to the drawings, and first with particular reference to the modification illustrated in Figs. 1 to 5, the layout depicted in Fig. 1 illustrates the relation of the elements contributing cates a fragmentary part of the engine base or frame that provides a well for receiving the stem or shank of an ignition distributor, the cup like housing of which is indicated at l2. Pivoted about the shank of the cup l2 there is abracket member M, an extension of which provides an arcuate slot I6 for reception of a holddown screw and tension device l8, that permits of oscillation of the bracket 14 within certain limits with respect to the engine base to. There is also provided a clamp arm 20 embracing the stem of the distributor cup l2, and maintained in rigid engagement therewith by means of a clamp screw 22 passing through one of the parallel extensions 24 and threaded into an oppositely disclosed extension 26. This organization provides a pair of plate members represented by the parts l4 and 20 both disposed about the shank of the distributor cup between the cup l2 and base in, and relatively movable through the agency of mechanism later to be described.

The distributor mechanism also embraces a shaft 36 having a geared relation with rotative erable with a movable contact 50 supported by the circuit breaker lever 34. Operation of the circuit breaker lever is perfected by reason of a rubbing block 52 that is periodically engageable by one of the crests of the rotating cam 32. The electrical connection of the circuit breaker is completed by means of a leaf spring conductor 54 secured thereto and wrapped about the insulated sleeve 36, the other end of the spring being secured under the head of a terminal screw 56 insulatinglysupportedin the wall of the cup of the current source is made.

The driving connection between the rotatable part of the engine and the cam 32 also includes a speed responsive mechanism that permits of angularly shiftable relation between the shaft 30 and the cam 32 in response to variations in engine speed, at i includes what is known as a weight base 58 provided with pivot posts 60 about which oscillate fiyweights 62 during variations of engine speed. The flyweights each provide a camming arm 64engageable with a cam bar 66 secured in rigid relation with respect to the cam 32. The camming portions of the fiyweight and cam bar are maintained in engageable rollable relation by means of a spring 68 hooked about the pivot post 66 and a rigid part 10 of the circuit breaker cam assembly. Inasmuch as the distributor mechanism thus far described is well known to those experienced in the art, it is not deemed necessary to go further into the discussion and description of the same. Therefore, sumce it to say, as the speed of the engine is increased, the flyweights 62 will be thrown out toward the outside of the distributor cup 12, and in doing so the cam arm 64 will rotate the circuit breaker cam 32 somewhat in advance of the rotation produced by the geared connection with the shaft 30, which will thereby effect an advance in circuit breaking through the points 48 l2, and to. which the usual electrical connection and 58 as the engine speed increases, all in accordance with the curve D appearing on the group of results curves, in Fig. 12.

The curve D in 12, sets out the basic spark I timing control relation mentioned earlier, and will hereinafter be referred to as the normal spark timing curve, over which additional timing adjustments are to be effective. In its entirety,

this normal or basic spark timing curve consists of a horizontal branch indicated by a and a uniformly ascending branch indicated by b. The branch (L is here shown to amount to about 18 advance for the initial spark setting, and extend-- ing throughout engine speeds from rest through idling engine speeds to about 14 M. P. H. engine are provided for effecting a spark timing control to be superposed upon the normal sparktiming curve. Contributing to this end, a fluid operated unit. or contraction chamber I2 is mounted upon an angular extension I6 of the bracket member I4, and is provided with means for rotating the distributor mechanism about the rotating cam. shaft 38, for additionally effecting a shift in spark timing. The contraction chamber 12 comprises a pair of cup like members 16 and I8, the peripheral edge of one of which is spun over the peripheral edge of the other, substantially as indicated at 88,- so as to clamp the edge of a membrane or diaphragm 82 therebetween, and provide a substantially fluid tight chamber 84 bounded by the cup' member I2 and membrane 82. Disposed within the fluid tight chamber there is a spring 86, one end of which seats within a cup or washer member 88, and that urges the diaphragm or membrane 82 away from the bottom of the cup member 12, so as to enlarge the chamber, yet permit a collapsing of the same upon exposure to reduced pressure. A link 98 is secured to the membrane 82 by means of a rivet 82 pasi'ng through the washer 88 and membrane, and clamping an extension of the link 98 thereto. The link 98 is notched or necked in at 84 and passes through an aperture or slot 96, provided by the angular portion I4 of the bracket member, whereby stops are provided that limit the overall movement of the link 98. The opposite end of the link 98 has a pivotal connection with a part 88 of the clamp arm 28.

This organization of elements is such that lineal movement of the link 98 through the slot 96 of the bracket member will produce relative rotation or oscillation between the plate members I4 and 28. Since the bracket member 54 is but loosely pivoted about the shank of the distributor cup I2, and firmly held in position on the engine frame member I8 by means of the tension device I8, and since the clamp arm 28 is rigidly secured to, and non-rotative with respect to the shank of the distributor cup I2, then, relative rotation or oscillation between the plate members I4 and 28, will likewise cause relative rotation or oscillation of the distributor .cup I2 with respect to the engine frame member ID. Thus, when oscillation ing timing advance or timing retardation upon the direction of relative movement with respect to the direction of circuit breaker cam rotation. If the. shift is in the same general direction as the direction of circuit breaker cam rotation, then the effected shift in timing will result in retardation, but, if the shift is in the opposite direction to that of circuit breaker cam rotation, then the effected shift in timing will result in an advance in timing, because in the latter instance the circult breaker operation occurs earlier in point ,of time than it otherwise would without the attendant shift.

For the purpose of actuating the membrane or diaphragm 82 of the contraction chamber, fluid connection is made between the chamber 84 and the interior of the engine induction pipe, and includes appropriate coupling means I88 joining one end of a pipe connection I82 to the interior of the cup member 12, and a second coupling device I84 by which-connection is made between the pipe I 82 and a part I86 of the fuel induction pipe I88. The part I86 constitutes an enlargement of one of the journal bosses on the exterior of the fuel induction pipe I88 for a shaft II8 of a butterfly throttle valve I I2. A cooperating journal boss I I4 is located substantiallydiametrically opposite to the boss I86, and both bosses are journaled at H6 and H8 respectively, to provide bearing surfaces for the throttle shaft II8.

A bore I28 is provided by the boss I86, which bore extends in a direction transverse to the axis of'the throttle shaft, and opens at an orifice I2I into the journal bore IIB for the throttle shaft. The outer extremity of the bore I28 is enlarged and threaded as at I22 for the reception of the coupling device I84. A second bore I24 which may be referred to as'a primary passage, is provided by the boss I86, and extends from the bore I 28 through the wall of the fuel introduction pipe I88, to open with an orifice I26. In forming this second bore I24, it has been found convenient to drill through the boss I86 from the exterior surface thereof and across the bore I28, substantially as indicated in Fig. 4. A sealing plug I28 is then driven in the start end of the bore to seal the passage against the entrance of outside air.

The location of the bores I28 and I24, and the orifice I26 are so disposed and proportioned, one with respect to the other, that the eifect of the fuel induction pressures within the member I88 can be critically controlled by rotation of the butterfly valve II2. It will be observed by reference to Figs. 1 and 2 that the primary passage I24 is so located as to be near the edge of the throttle valve I I2 and wholly upon one side thereof when the throttle valve is closed, but will be transferred to theopposite side of the throttle valve when the throttle valve has been slightly opened. A throttle valve of the type illustrated, divides the fuel induction pipe into what may be characterized as a high pressure zone I38 on the carburetor side of the throttle valve, and a low pressure zone I32 on the engine side of the throttle valve. This condition will obtain so long as the throttle valve offers any material resistance to fluid movement through the pipe I88 from the carburetor side to the engine side of the valve. In each of the illustrated embodiments, in which a down-draft carburetor is illustrated, the high pressure zone will be represented by that portion of the fuel induction pipe above the throttle valve II2, while the low pressure zone will be that portion beneath the said throttle valve. Consequently, referring to Fig. 1, when the throttle valve I I2 is closed during engine idling conditions, the primary passage I 24 will open into and'be exposed to the high pressure zone, on the carburetor side of the throttle valve; and when the throttle valve has been opened sufficiently as illustrated in Fig. 2 to transfer the port I23 to the opposite side of the throttle valve the primary passage I24 will thence open into the low pressure zone, on the engine side of the throttle valve. During the interim of changing the throttle position from Fig. 1 to Fig. 2, there will be a gradually effected change of pressure operating at the orifice I26. The changes are rapid, and the transition period is of such short duration that the resultant movement of the diaphragm within the contraction chamber is comparatively abrupt.

The resultant spark timing control, effected by a mechanism having in substance a single port in the fuel induction pipe located near the edge of the throttle valve and so situated as to be transferred to the opposite sides thereof upon opening the throttle valve, is suificiently satisfactory to be incorporated for control of spark timing, over the lower speeds of the engine speed range. The spark timing curve effected by a mechanism of that character is indicated by the full line ad- Vance curve E of Fig. 12, and comprises the rapidly ascending branch 0, joined by the substantially straight portion (1, and the recurved portion e. t

In Fig. 11, there are represented conditions curves, in which curveA is a vacuum curve for an automatic spark timing mechanism incorporating a single port or connection to the fuel induction pipe, of the character thus far described. It will be observed that this curve A has a comparatively rapid ascent from about 2 inches mercury depression at an engine speed of about 8M. P. H. to about 18 inches mercury depression at an engine. speed of about 25 M. P. H. The resultant of this rapidrise of vacuum potential is manifest in the comparatively abrupt shift, and slightly too early shift, of spark timing for the lower engine speeds. The corresponding spark timing shift effected by a mechanism so characterized, is represented by the branch of the advance curve E shown in Fig. 12.

It will also be obsenved that the vacuum curve A in Fig. 11 flattens out somewhat and assumes a long gradual slope for engine speeds extending from. the crest of the curveat about 32 M. P. H., through extreme high speeds. In general, the moment of-force represented by the diminishing branch of the vacuum curve A is too powerful, and is too. long continuing to produce the desired spark timing control for the higher engine speeds, particularly for those engine speeds greater than about 50 or 60 M. P. H. The spark timing advance resulting from the downwardly sloping'portion of vacuum curve A. is particularly illustrated by the recurved portion e of the advance curve E shown in Fig. 12. The undesirable portion of the advance extends from about 52 M. P. H. through the higher speeds.

The instant invention contemplates improving the control of ignitior timing at both the,low and high speed end of the range of engine speeds, by producing a more gradual shift of automatic timing over the centrifugal timing' at the end of engine idling speeds, and by diminishing and graphically illustrated by the conditions curve B- of Fig. 11, and the 11sults curve F of Fig. 12. The dashed line curve B represents the vacuum to which the fluid. connection of the contraction chamber is exposed when applicants invention is incorporated, the curve B comprising an upward sloping portion g of less steep beginning, and

more. uniform rate of increase than the vacuum curve A, and with a downward sloping portion h of considerably steeper slope, and in all, extending over muclr less range of engine speeds, than the full line vacuum curve A. The interpretation of this dashed line curve 13 means that the vacuum potential within the fuel induction pipe will be of less abrupt efiect for the lower speeds of the engine range, and will be of shorter duration, and of less moment during the higher engine speed, such that a substantial retraction of the contraction chamber may be secured for much lower engine speeds.

The resultant spark timing is represented by the curve F appearing in Fig. 12 where the dashed line portions represent the corrected spark timing relation at each end of the curve E, produced by applicants' improved mechanism. The intervening fiat portion of the graph E is commonwith respect to both the full line advance curve, and the dashed line-advance curve F. The dashed line portion F at the lower end of the revised spark timing curve, illustrates the more gradual shift of advance in timing, while the dashed line portion F of the curve extending between 52 and 60 M. P. H. illustrates the cut-off of spark timing for the higher engine speeds, due tothe improved mechanism. By comparison of the two curves, it will be observed that the corrected advance of timing at about 12 M. P. H. is by the curve F about 20 ahead of top dead center, as

compared with an advanceof about 23 or more at the same speed by the curve E.

There appears on both Figs. 11 and 12 a curve designated C that represents the position of throttle opening for the various engine speeds. Two scales are associated with this curve 0, one of which is-graduated in degrees of throttle opening, appearing at the left hand margin of the figure, while the second scale is in percent of throttle opening, appearing at the right hand margin of the figure. For the purpose of comparison, the road torque throttle curve C is reproduced in both Figs. 11 and 12. v

The improved novel construction for accomplishing the advance cut-off at the high speed end of the engine speed range, is illustrated in detail in Figs. 4 and 5. An interruptible passage is provided that operates to connect the primary passage I24 to the high pressure zone I30 of the fuel inductionpipe, at a point in the throttle opening where it is desired to effect the advance into the interior of the fuel-induction pipe I08 I and situated on the carburetor side of the throttle valve. The other end of the passage I34 ends with an orifice I38 at the surface of the shaft IIO within the bearing bore 6, ofthe boss I06,

at such a point along the extent of the bore that the port I38 may be aligned with the open end or orifice I2I of the passage I20 at a certain angular position of throttle opening.

Referring to Figs. 1, 2 and 3, the relation of the ports and passages, contributing to the completecontrol of spark timing advance, will be observed to be such that in the idling position of the throttle M2, the contraction chamber I2 will be completely expanded, substantially as shown in Fig. 1, to give the initial spark timing setting represented by the branch a of curve D in Fig. 12. This is because the fluid connection of the chamber 04 is exposed to the high pressure zone 330 of the fuel induction pipe, due to the primary passage us being situated on the carburetor side of the throttle valve. Under these conditions of engine operation, that is when the throttle valve H2 is closed for idling, the high pressure zone I30 is substantially the same as atmospheric pressure. There is then, no fluid displacement within the chamber 84, by which a mechan ical shift between the parts I4 and 20 could be effected, and consequently, the relation of the circuit breaking mechanism and operating cam is unaltered.

The contraction chamber I2 has been calibrated to operate upon about 5 inches of mercury displacement, and it will be observed by reference to Fig. 11, and the dashed curve designated B,

that this mercury displacement of 5 inches occurs at about M. P. H. On reference to' Fig. 12, it will be noted that at the speed of about 10 M. P. there begins to be an advance in timing according to the advance curve F, and that the advance in timing effected is continuously increasing throughout an increased engine speed up to about 14 M. P. H., the total amount of advance being about 17 over and above the advance produced by the centrifugal mechanism represented by curve D, there being a total advance; for an engine speed of about 14 M. P. H.,

completed at a throttle opening of about 7,

which is equivalent to 8% to 9% of the total amount of throttle opening.

Thus, it will be seen'that the advance in ignition timing over the centrifugal mechanism for the low engine speeds, is the result of slightly increased opening of the throttle valve from the substantially closed or idling position illustrated in Fig. 1 toward that position illustrated in Fig. 2. However, the complete shift is effected at a point a little more than half way between the illustrated throttle openings of Fig. 1 and Fig. 2. The throttle opening illustrated in Fig. 2, amounts to an opening of about 12 above the position illustrated in Fig. 1, which amounts to about 15% throttle opening, and which occurs at about .25 M. P. H. engine speed, as will be seen by reference to the curves C appearing in Figs 11 and 12.

The total amount of suction created spark tim- -ing shift over the advance by centrifugal mechthese elements of structure, make it possible to introduce an advance in spark timing by a suction control at about 10 M. P. H. engine speed, which control will gradually advance the timing to about 17 above the advance by the centrifugal mechanism, occurring at about 14 M. P. H., at which point the stops 90 and 36 will have been engaged, and from thence on maintain a fixed amount of timer, shift over and above the advance in timing by the centrifugal mechanism during further increased engine speeds.

Upon reference to Fig. 12, it will be noted that at speeds from 50 to 55 M. P. 11., it is desiredto limit any further advance in timing, and that for speeds between 55 and 60 M. P. H., it is desired to reduce or cut off all of the suction controlled advance, such that spark timing control for increased engine speeds may be wholly effected by the centrifugal mechanism, and in accordance with the characteristics of the upper portion of the advance curve B. On reference to curve C, it will be noted that at 52 M. P. at which point 'it is desired to prevent any further advance in automatic timing, that the throttle valve is opened about 30, which is equivalent to about 37 /z% throttle opening. For this same throttle opening and road speed, it appears from tion chamber to retract under the influence of the spring 86, since the contraction chamber "I2 remains in the collapsed state for all pressure potentials greater than about 5 inches mercury depression.

Therelation of the contributing elements effecting this high speed control is illustrated particularly in Fig. 3, where the throttle valvel I2 has a 30 opening, which isequivalent to about 37 /270. Rotation of the throttle valve from the vposition illustrated in Fig. 1, to that position shown in Fig. 3, is accomplished by rotation of the shaft H0, and necessarily brings the orifice. I38 of the cross bore I34 into communication with the orifice I2I at the bearing surface end of the bore or passage I20. Orifice I36 of the passage I34 always opens into the high pressure zone I30 of the induction fuel pipe, and it will thence be observed by reference to Figs. 3 and 4, that at the 30 throttle opening position, communication is established between the high pressure zone I30 and the passage I20 by means of the cross bore I34. Since the passage I20 and its fluid connection to the chamber 12 is exposed to the low pressure zone I32 through the primary passage I24, then the potential of the pressures within the induction pipe, both above and below the throttle valve, combine within the passage I20, the influence of which is transmitted to the contraction chamber I2.

As the throttle shaft approaches the position illustrated in Fig. 3 and continues in the opening movement, a greater modification of the pressure within the passage I20 is effected. ,lAS the throt-' tle valve is opened there will be some valving effects in the interruptible passage due to the widening of the edges of the parts providing the orifices for the passages I 34 and I20. In Fig. 3 this valving effect is illustrated to the effect that the orifice I30 is only partly opened to the orifice I2I in consequence of which a restriction is provided that permits only apartial modification of the pressure in passage I20. The potential of the high pressure zone of the passage I34 is but partially effective upon the potential of the low pres-. sure zone through the passage I 24. As the throt tle valve H2 is opened wider to a point where 5 this restriction is done away with, then the potential of the high pressure zone becomes fully effective and cancels the effect of the potential of the low pressure zone, to which the passage I20 is exposed through passage I24. This condition occurs when the throttle valve is about half opened or at an angular setting of about 40 beyond the closed position of Fig. 1. 0n reference to Fig. 12 it will be observed that this condition occurs at speeds of about 60 M. P. H., or a little 15 more, at which point all spark timing advance by means of the contraction chamber is done away with, as represented by the upper branch of the curve F where it joins the curve E at f.

In Figs.'6 to 10 inclusive, there is illustrated a modification of the construction for effecting the control at-the high speed end of the range of engine speed. All parts of this construction in common or similar to the modification thus far described, are designated by the same reference characters, while the elements of construction differing from those of the modification bear reference characters of the order of 200. The fuel induction pipe I08 is provided with a boss 206 through which there is the bore II6 providing one journal for the throttle shaft IIO.- A bore 220 is here provided that extends across and somewhat beyond the journal bore II 6, and constitutes an elongation of the bore I20 of the first modification, the starting end of the bore 220 being likewise threadedat I22 for reception of the coupling unit I04. In addition to the primary passage I24 opening into a high pressure zone above the throttle valve II2 when closed, there is a second bore 225 leading from the far end of the bore 220 and ending with an orifice 22'I, situated so as to open into the high pressure zone I30 of the fuel induction pipe. The starting end of the bore 225 is closed by a plug 220 as in the instance of the primary passage 'I24.

Here the throttle shaft H0 is provided with a the high pressure zone of the fuel induction pipe.

Fig. 7, illustrates the parts in throttle closed position where it will be observed that both passages I24 and 225 open to the high pressure zone on the carburetor side of thethrottle valve I I2.

However, due to the fact that the orifice m of the cross bore 234 is closed off by the bearing surface IIB, there is no communication between opposite ends of the passage 220, and hence any contraction chamber that might be connected to the passage 220 at the threaded portion I22, is

subjected to the high pressure zone of the fuel induction pipe only through the passage I24. The potential of the high pressure zone being insuflicient to actuate the membrane 82 of the con- 7 traction unit, there will then be no shift in ignition timing.

In Fig. 8, the throttle valve has been adjusted to about a 12 opening, and in which instance the primary passage I24 is in effect transferred to the 75 low pressure zone of the fuel induction pipe, or is v disposed on the engine side of the throttle valve.

The low pressure zone has become suiiiplently effective upon the contraction chamber long ere this throttle position is reached, to effect the initial advance in timing over the basic timing curve, as has been explained hereinbefore 0n reference to Fig. 12 it will be recalled that this shift takes place between 10 and 14 M. Pl H. It will also be observed that the cross bore 234 still fails to provide any communication between the opposite ends of the passage 220. However, when the throttle valve II2 reaches a throttle opening of about 30, which is illustrated in Fig. 9, there is sufllcient communication established between the opposite ends of the passage 220 to permit of some modification of the pressure potential upon the contraction chamber. Though the primary passage I24 opens into the low pressure zone of the fuel induction pipe, and in itself is sufilcient to effectively operate the membrane 82 of the contraction chamber, the effective potential of the low pressure zone is modified by the potential of the high pressure zone through the passage 225 which always opens into the high pressure zone of the fuel induction pipe. That high pressure potential is beginning to become effective through the cross bore 234, by reason of which there is a modification or reduction of the pressure moment in the fluid connection to the contraction chamher. This isillustrated by the curves D, F and C appearing in Fig. 12, as has heretofore been explained.

In Fig. 10 there appears a layout of the principal elements of-construction showing the relation of parts when the throttle valve is wide open. When the throttle valve is wide open,

there is such insuflicient restriction of commu-- nication between'the passages I24 and 225, and through the cross bore 234. that there is insufficient force to draw in the diaphragm or membrane 02. In consequence of this, the spring 06 retracts the membrane to the rest position, which results in cancellation of any advance by suction mechanism. This retracted position of the membrane of the contraction chamber takes .place as soon as the throttle valve has been opened sufliciently for the potential of the high pressure zone to cancel the potential of the low pressure zone. Upon reference of Fig. 12, it will be observed that this cancellation takes place when the throttle valve is about half way opened.- Note, for instance, that the lower end of the advance curve F intersects the centrifugal ad'- vance curve D at the point i, which is at about 60 M. P. H.- The curve C indicates that the throttle valve is opened about 40 or 50% of the total opening.

While the embodiment of the present inven- 2 tion as herein disclosed, constitutes a preferred form, it is to be understood that-other forms rendering the suction controlled means non-responsive to suction potential while the throttle is positioned at the high speed end of the engine speed range.

- 2. The combination with an internal combustion engine having a throttle, and an ignition timer for said engine, of means controlled by the suction of said engine for adjusting the timer, and means including an interruptible passage for diminishing the effect of the suction control when the throttle is positioned for the higher speeds of the engine speed range.

3. The combination with an internal combus-' tion engine having a throttle, and an ignition timer for said engine, of means controlled by the suction of said engine for adjusting the timer, and means including a, normally closed passage for cutting off the suction effect during throttle opening for high speed engine operation.

a. The combination with an internal combustion engine having a fuel induction pipe, a throttle valve dividing the pipe into a high pressure zone and a low pressure zone, ignition timer mechanism, and means influenced by the vacuum created in the fuel induction pipe, when-the engine is operating at throttle opening giving speeds above idle speed for altering the timer mechanism, of connecting means between the altering means and the induction pipe for oper-- ating the timer altering means in response to the potential of the low pressure zone, and means including an interruptible passage leading to the 3 high pressure zone of the induction pipe for cutting oii the potential of the low pressure zone to the connecting means during engine operation under throttle opening over the upper third portion of the engine speed range above idling.

5. In an internal combustion motor, having an intake passage in which suction is created by operation of the engine, the combination com-v prising, an ignition timer, movable means for shifting the timer for timing the ignition, said movable means being actuated by the suction potential created in the intake passage, with a lay-pass to a higher pressure within the intake pipe for variably controlling the effective suction on the timer shifting, means whereby the suction will be insufiicient to operate the movable means during the extremes of throttle opening, said means operating to cause an effective tension on the movable means to effect a sudden advance in spark timing at a throttle position just above the idlespeed band, and to effect a sudden retard in spark timing just prior to throttle opening for the high speed extreme of the engine speed range.

6. In an internal combustion motor, having an intake passage in which suction is created by operation of the engine, the combination comprising, an ignition timer, movable means for shifting the timer for timing the ignition, said movable means being actuated by the suction potential created in the intake passage, with a bypass to a, higher pressure within the intake pipe for variably controlling the efiective suction on the timer shifting means whereby the same will be insufficient to operate the movable means during the extremes of throttle position, said means operating to cause 'an effective tension on the movable means to effect a sudden advance in spark timing at about 6% engine throttle opening, and to effect a sudden retard in spark timing at about 40% engine throttle opening.

'7 In an internal combustion motor, an intake passage in which suction is created by the running of the motor, an igniter including a movable timer element for timing the ignition, a movable device including a suction responsive chamber, with means for actuating the timer element, a connection between the chamber and the intake passage, an interruptible passage opening into the connection, a throttle valve in the intake passage dividing the passage into high and, low pressure zones, said suction responsive chamber being exposed to the high pressure zone of the intake pipe while the throttle is opened during engine idling operation and thereby effecting no timer alteration, movement of the throttle valve exposing the chamber to the low pressure zone of the intake passage at throttle positions greater than about 10% of the total throttle opening, thereby effecting a timer alteration for all throttle positions above that for idling speed, and means including the interruptible passage exposed to the high pressure zone for/v cancelling the timer alteration by the suction chamber while the throttle is-opened during the higher third portion of the engine speed range above idling. I

8. In an internal combustion motor, having an intake passage in which suction is created by the running of the motor, and in which a throttle valve divides the passage into a high pressure zone and a low pressure zone, the combination including an igniter provided with a movable timer element for timing the ignition, means providing a normal timer control in accordance with a basic timing curve, a chamber operable upon the timer element with means for putting said ing engine operation under practically wide open throttle.

9. In an ignition controller, the combination with an engine having a fuel induction pipe, and a throttle valve in the fuel pipe providing high and low pressure zones on opposite sides thereof, of an ignition timer, a suction device for setting the same, means connecting the device with the fuel induction pipe and comprising, a passage with a port opening into the high pressure zone of the fuel pipe when the throttle valve is closed, but shiftable to the-low pressure zone as the throttle valve is opened for engine speeds above idling, and a branch passage with an interruptible portion provided by the throttle valve, adapted to open into the high pressure zone at predetermined throttle positions, whereby the device will fail to respond to the potential of the high pressure zone for throttle positions less than about 6% and more than about 50% of possible throttle opening, but will respond to engine produced suction between 6% and 50% of possible throttle opening to efiect setting of the ignition timer.

10. In an ignition controller, the combination with an engine having a fuel induction pipe, and

a throttle valve in the fuel pipe providing high and low pressure zones on opposite sides thereof, of an ignition timer, a suction device for setting the same, means connecting the device with the fuel induction pipe and comprising, a passage with a port opening into the high pressure zone of the fuel pipe when the throttle valve is closed, but shiftable to the low pressure'zone as the throttle valve is opened for engine speeds above idling, and a branch passage with an interruptible portion provided by the throttle valve, adapted to open into the high pressure zone at predetermined throttle positions, whereby the device will fail to respond to the potentials of the fuel pipe for throttle positions up to about '6% opening and for throttle positions above about 50% of possible throttle opening, but will respond to engine produced suction for throttle positions between 6% and 50% of possible throttle opening to effect setting .of the ignition timer,

11. In an ignition controller, the combination with an engine having a fuel pipe, and a throttle valve on a shaft journalled in bosses pro-- vided by the fuel. pipe, and separating the pipe into high and low pressure zones, of an ignition timer, a suction device for setting the same, means connecting the device and the fuel pipe, and including passages located in one of the fuel pipe bosses and the throttle shaft for selectively exposing the device to the potentials of both pressure zones in the fuel pipe, the passage in the throttle shaft having interruptible communication with the passage in the boss and always opening into the high pressure zone of the fuel pipe, for cancelling the effect of the low pressure zone upon the device at a predetermined throttle opening.

12. In an ignition controller for internal combustion engines; the combination of, a timer device, and means controlled by the suction of the engine, having provisions for obtaining a relatively quick advance of spark at about 5% engine throttle opening, and a relatively quick retard of spark at about 40% to 50% engine throttle opening, andmeans establishing a basic spark timing curve, from which the provisions effect the advance, characterizing a uniform angular relation for engine speeds up to about 7% engine throttle opening, and thence a substantially uniformly advancing speed controlled relation up to about engine throttle opening, said provisions effecting a predetermined timer advance above the basic timing substantially throughout the throttle opening range between about 5% and 50% engine throttle opening.

13. In an internal combustion motor, having an intake passage in which suction is created by operation of the engine, and in which a throttle valve tends to separate the passage into high and low pressure zones during engine operation, and having an ignition timer with suction responsive means for controlling the ignition timing, the combination of means regulating the application of suction from'both zones to the suction responsive means, said-regulating means including an uninterrupted primary passage opening into the high pressure zone of the intake passage and near the edge of the throttle valve at less than 6%throttle opening, an interruptible by-pass for the primary passage that remains closed up to about 40% throttle opening, whereby a rapid automatic advance in ignition timing is effected at about 6% throttle. opening, and a diminution of timing advance is effected for 40% or greater throttle opening.

14. In an internal combustion engine having a fuel pipe provided with a throttle valve, separating the pipe into high and low pressure sides, said fuel pipebeing subject to variations in engine produced suction incident to self-operation, ignition apparatus comprising in combination, a circuit breaker, a cam for operating the breaker, and means responsive to engine produced suction for varying the angular relation between the cam and breaker, said means including a suction chamber having communication by a. primary passage with a port in the fuel pipe located onthe high pressure side of the throttle valve and near the edge of the valve when closed, but. exposed to the low pressure side of the throttle valve when the valve has a 6% or greater opening, and means providing a secondary passage joining the primary passage and having interruptible communication with the high pressure side of the throttle valve for modification of the pressure in the primary passage at 40% and greater throttle openings.

- 15. The combination set forth in claim 14, in which the means providing the interruptible communication include a cross bore in the throttle shaft continually exposed to the high pressure side of the fuel pipe and one end of which normally ends at the bearing surface of the throttle shaft, and which is alignable with a branch of the primary passage at a predetermined point of throttle opening.

16. In an automatic timing control for ignition distributors, the combinationcomprising, a timer having'a movable part for altering the time of ignition, an expansion chamber adapted to actuate the movable part, a fuel induction pipe provided with a rotatable shaft supported throttle valve for admitting fuel to the engine cylinders, and means connecting the chamber with the in- I duction pipe, said means including a boss on the induction pipe surrounding the throttle shaft and providing a passage ending at the surface of the shaft, and a lateral branch of the passage opening into the induction pipe adjacent the edge of the throttle so as to be exposed to the carburetor side thereof when the throttle valve is closed, but exposed to the engine side of the throttle valve when opened greater than for idling, and means including a passage provided by the throttle shaft,,and registrable with the first mentioned passage end, for exposing the connecting means to the carburetor side of the induction pipe during 40% or greater throttle opening.

17. In an automatic timing control for ignition distributors, the combination comprising, a timer having a movable part for altering the time of ignition, an expansion chamber adapted to actuthe shaft is rotated toward open position, one a end of the throttle shaft passage always being open to the carburetor side of the induction pipe, while the other end thereof is closed oil by the shaft bearing surface during throttle closed positions less than about 40% and greater throttle opening.

18. In automatic control mechanism for ignition timers, wherein an expansion chamber is in communication with the fuel induction pipe and responds to the suction potential within the fuel induction pipe for shifting the time of igniupon the chamber, whereby the chamber will be non-responsive to the suction potential below 6% and above 53% throttle opening for effecting a predetermined shift in ignition timing, said connecting means including a passage opening into the fuel pipe at the edge of the throttle valve and exposed to the engine side thereof when the throttle valve is opened more than about 6% of total throttle opening, a second passage opening into the fuel pipe and always exposed to the carburetor side of the throttle valve, but normally out of communication with the first mentioned passage, and means including rotation of the throttle shaft for establishing communication between the passages at a predetermined throttle opening, whereby the connecting means to the chamber is subjected to a resultant of the suction potentials on both sides of the throttle valve at and above about 40% throttle opening. 19. In mechanism for controlling ignition timing in response to the suction potential within an engine intake pipe, the combination with the intake pipe of a butterfly throttle valve, a rotatable shaft supporting the valve and having bearings in the walls of the pipe, means providing a passage having a port opening into the fuel pipe at the edge of the valve so as to be exposed to low pressure potential when the valve is opened beyond about 6% of its possible opening, said passage ending at one of the bearing surfaces for the rotatable shaft, and a passage provided by the shaft for exposing the first mentioned passage to a high pressure potential within the intake pipe when the throttle valve is more than about open.

20. In mechanism for controlling ignition timing in response to the suction potential within an engine intake pipe, the combination with the intake pipe of a butterfly throttle valve, a shaft journaled in bearing bosses provided by the pipe, for rotatably supporting the butterfly valve across the pipe, said throttle valve tending to separate the pipe into high and low pressure zones, a passage provided by one of the bearing bosses having a port opening into the pipe near the edge of the butterfly and exposed to the high pressure zone while the butterfly valve is substantially closed, but exposed to the low pressure zone of the intake pipe as the butterfly valve reaches a 6% opening, and means including a passage through the shaft for exposing the first mentioned passage to the high pressure zcne of the intake pipe as the butterfly valve reaches a 40% opening.

21. In a suction controlled timer for internal combustion engines wherein an expansion chamber has fluid connection with an induction fuel pipe, the combination with the flui'd connection of means exposing the connection to relatively high pressure within the fuel pipe while the throttle valve is nearly closed, and to relatively low pressure for increased throttle openings, and means exposing the connection to both high and low pressures within the fuel pipe at apredetermined throttle opening, whereby the suction control is rendered non-effective for substantially wide open throttle operation.

22. The combination with an internal combustion engine having, a fuel pipe, a butterfly throttle valve therein, and an ignition timer for said engine, of means controlled by the engine suction produced within said fuel pipe for adjusting posed to the carburetor side of the throttle valve when open less than 6%, means for expos the said port and passage to the engine side of the throttle valve as the valve is opened more than 6%, and means comprising an additional passage for exposing the first numbered passage to the carburetor side of the throttle valve at about 40% throttle opening.

23. The method of controlling the suction admitted to the suction unit of a timing control mechanism for internal combustion engines, having. a fuel induction pipe with a throttle valve, a timer, and a suction unit for shifting a timer part, said method comprising the steps in combination, subjecting the unit to the relatively high pressure only on the carburetor side of the throttle valve While the valve is but slightly open, subjecting the unit to the relatively low pressure only on the engine side of the throttle valve, while increasing the throttle opening from slightly open to almost half open, and thence, also subjecting the unit to the relatively high pressure on the carburetor side of the throttle valve as the open ing of the throttle valve is increased to the half. open position.

24. The method of controlling automatic tim ing for internal combustion engine, comprising the steps in combinations, establishing fluid connection between a contraction chamber and a high pressure zone of the full induction pipe, while the engine throttle is practically closed, shifting the fluid connection from the high pressure zone to a low pressure zone of the fuel induction pipe as the throttle is opened slightly beyond the practically closed position, and thence opening the fluid connection to the high pressure zone without disturbing the connection to the low pressure zone as the engine throttle approaches the half open position.

25. The method of controlling the movement of a suction operated device for shifting the timing of an internal combustion engine, comprising the steps of bringing the device into fluid communication with a relatively high pressure zone of the engine intake pipe while the throttle valve is substantially closed, Shifting the fluid communications from the said high pressure zone to a relatively low pressure zone of the intake pipe, as the throttle valve is slightly increased in opening, maintaining communication with the low pressure zone for all throttle positions greater than the slight throttle opening, and also making a fluid communication with the high pressure zone of the engine intake pipe before the throttle is increased to half open position without interrupting the communication with the low pressure zone. 5

26. The combination with an internal combustion engine having a fuel pipe, a butterfly throttle valve therein, and an ignition timer for said engine, of means controlled by the engine suction produced within said fuel pipe for adjusting the timer, and means modifying the control by suction, said modifying means including means effecting a retard of spark timing during'engine operation with slightly opened throttle, comprising a port and passage opening into the fuel pipe and exposed to the carburetor side of the throttle valve when open less than about 6%, means effecting a substantially fixed amount of advance in spark timing for engine operation with more than slight throttle opening, comprising means for exposing the said port and passage to the engine side of the throttle valve as the valve is opened more than about 6%, and means- 75 high pressure within the fuel pipe while the engine is operating under slightly open throttle, and to relatively low pressure for engine operation at throttle openings more than slightly open, and means exposing the connection to both high and low pressures within the fuel pipe at a predetermined throttle opening, whereby the suction control is rendered non-effective 'during engine operation under substantially wide open throttle.

JAMES L ARTHUR, 

